Mesopotamian art

A ruler's claim to divinity can be expressed in three ways: his name may be preceded by the cuneiform sign for God, in the same way as other deities names are, and his headdress may be represented with horns, the mark of s god in the iconography, and in a variety of ways evidence may be seen that he was worshipped by the population in a cult of his own. ... Ur III cylinder seals offer a depiction of this scene, but they do retain a very marked distinction between the real god and the king: the king's seat is not the converted altar of the gods, but a stool over which a fleece has been spread, and he wears his royal hat, without any trace of horns. Postgate, p 206